The present invention relates to a selective light-transmissible film or sheet which has good transparency in the visible ray region, high infrared ray reflectivity and moreover has excellent anti-fogging properties.
In recent years, it has been desired to render windows highly heat-insulative (or infrared ray screenable) from the viewpoint of energy saving for windows of air-conditioned buildings and refrigerator showcase windows, and from the view point of comfortability in summer for vehicles such as automobiles.
Means to render windows to have such heat insulation include:
(1) use of multiple-glazed windows, PA1 (2) use of infrared ray reflective glass, PA1 (3) adherence of infrared ray reflective film to windowpanes,
etc.
The method of using infrared ray reflective film is less expensive in comparison with the other methods, and the film has excellent heat insulation. As for the so-called selective light transmissible film produced by superposing a thin film of metal such as Al, Au or Cu etc. on a transparent plastic film such as that of polyethylene terephthalate, or further laminating such a metallic film with a transparent dielectric layers of a high refractive index so as to make it suitably pass visible rays and reflect infrared rays, many proposals have been made such as Japanese Patent Publication No. 59147/85, Japanese Patent Publication No. 1296/86, Japanese Patent Kokai No. 117228/83, Japanese Patent Kokai No. 35943/86, etc.
These prior techniques are effective in providing heat insulative films which suitably transmit visible rays and reflect infrared rays. However, when they are adhered to the inside of windows of buildings, automobiles, cool showcases, etc., anti-fogging properties of the inner surface of the film can not be expected, that is, water droplets condense on the film surface and impair the transmission of visible rays.